I've had my FR-S since May 2012 and it's my daily driver and sole vehicle currently with nearly 40k miles. Overall it has been pretty reliable, never leaving me stranded at least. Not to say it hasn't been without some issues.
Issue #1 - an ECM failure. Idle was hunting and getting worse then when I was at the Texas 86 meet in 2014 after the oil temp got to about 240F and did some high rpm shifting the car started running rough and wouldn't disable the VSC or TCS systems. Luckily was using a Scan Guage to display temps and other data, so was able to clear codes and get it to run normally - until car was driven 'too hard' again with too high a load at anywhere above 215F oil temps. So to keep from going into limp mode had to baby the car 100% of the time and shift at low rpms. Took car into dealership and the ECM was replaced under warranty with updated ECM...I had one of the very early production cars with known bad ECM/mapping if high rpm's were seen. New updated ECM/Mapping fixed the issue...maybe.
Issue #2 - So within a weeks time the check engine light came back on, but at least this time VSC and TCS were not affected - they could still be "turned off" (which is how I normally drive the car all the time). P0351 code...if you drive the car hard, or track the car, or drive in a HOT climate you will eventually get this code. Car drives normally, maybe just barely perceptably with a little hesitation. Basically your ignition coil/spark plugs can't take the heat of the enclosed engine bay. There has not been a proven solution to this issue, anything you can do to vent the heat out seems to help though. If you plan on tracking the car then plan on adding coil packs as a consumable item.
I have bought a spare coil pack but not installed it, car runs fine and I can clear the code with my Scan Guage if needed. Runs fine without any code throwing in the cold months, once we get into spring and summer though put too much load on the engine with a fast acceleration and will throw code. Reason holding off on coil pack replacement is I am going to vent the hood first...and the vents I want that have been aerodynamically tested along with thermal data are about to be released and available.
Issue #3 - when the weather changes, mostly from cooler/ drier to warmer/more humid, and you first start the car - the first stop you make with it afterwards, it dies. Will restart with a some effort but run fine with no issues afterwards.
My FR-S was only ever tracked once, and that was about one month after first getting it; once it was "broken it in" and the fluids changed. Been daily driven since.
For me I will say I bought the car in spite of the fact I think the factory drivers seat is horrible. 6'2", 34" inseam, ~180lbs...main issue is the factory seat bottom is non adjustable in rake and barely has any. And for as low as the seat position is supposed to be, it's still 2" too high...have to bend my neck down a little and look up just to see traffic lights. Stock seat is my #1 complaint about the car...uncomfortable for any ammount of time, but especially for anything over about 20 minutes.
My solution was to save up and get a proper decent seat - Recaro Sportster CS. Made some custom brackets for a Recaro slide to fit it in...only thing is you gain barely any drop with aftermarket seats unless you hard mount them or are going to side mounted racing seats, so still need to crouch some to see intersection signals hidden by the roof. The Recaro's make ALL the difference in comfort and control though, besides feeling nice to sit in you also are connected like you are a part of the chassis with them as opposed to sitting on a seat that's on the chassis. Stock seat was an 'on the seat' driving experience, not a 'in the seat' or actually 'IN THE CHASSIS!' experience like I have with the Recaro.
I'll come out and say it now, I love the car and there is NO other car I want to drive or actually would consider replacing it with. It may be a little rough around the edges and require a little customization for driver fitment, but I've yet to drive a car that was perfect and most factory seats are terribte to me. The CHASSIS lets you forgive everything else about it.
It rides well on the highway (once you stiffen up the motor and transmission mounts and add in a tower brace) - it's an excellent little GT car that effortlessly cruises and gets good mileage doing so (solid 31mpg @ 80mph). Daily driving I average about 21mpg nominally, it's just too much fun to worry about fuel numbers - if I do restrain myself I could push it up to about 26mpg. The balance of the chassis is just very exact and linear, with nice feedback from the steering (once you get rid of the laughably horrible stock steering rack bushings and replace them with ones that keep it from moving around all the time.) It's honestly amazing how good a steering feel it has on the poor stock steering rack bushing design that can't even properly locate and control the steering rack...
As long as you keep the wheels and tires to better and lighter than stock, the ride quality, balance, and responsiveness gets noticeably better...
The FR-S is for the driver that doesn't mind putting up with some issues that for the most part aren't too major and making some changes if needed for ergonomics in exchange for a driving experience that is unlike most anything else. I've had mine for nearly 4 years, and I like it more now than ever before. Every drive as exciting as the last, NO MATTER WHAT!